In higher animals glycerolipids are synthesized either via glycerophosphate or via acyldihydroxyacetone phosphate. Acyl dihdroxyacetone phosphate is also the precursor of all glycerol ether lipids (alkyl glycerol ethers and plasmalogens). In a preliminary study it was found that the enzymes of acyl dihydroxyacetone phosphate pathway were mainly localized not in mitochondria or microsomes, (the organelles previously held to be the site of all lipid biosynthesis) but rather in microbodies (peroxisomes), a sub-cellular organelle in which no lipid biosynthetic enzyme had been described. The major objective of the proposed research is to establish conclusively the presence of the enzymes of the acyl dihydroxyacetone phosphate pathway for glycerolipid (ester and ether linked) biosynthesis in the microbodies of liver and brain and to study the role of microbodies in overall glycerolipid metabolism in cells. A detailed investigation of the presence of different enzymes catalyzing the metabolism of glycrolipid will be made and methods will be developed for the preparative isolation of brain microbodies (microperoxisomes). The effect of the hypolipidemic drug clofibrate, which is known to cause a proliferation of peroxisomes in liver, on the activity of lipid metabolizing enzymes in microbodies as well as other physiological parameters such as fasting or high carbohydrate diet which are known to affect lipid metabolism and microbodies in tissues will also be studied.